CAN - Multiplexing Worksheet

2001 Range Rover/Land Rover

Twisted pair was in the ABS control unit.

yellow/black and yellow/brown

Record the waveform of the wires. (Make sure your time is small enough so you dont have "aliasing") 

Channel A:                                     Channel B:

Time per division 50us                      Time per division 50us

Voltage per division 2v                      Voltage per division 2v

What is aliasing? Describe it.

It is when to different signals become indistinguishable from one another when trying to capture or read them.

These two signals are clearly not aliasing each other you can see one signal is being pulled up and one signal is being pulled down.

Channel A: main voltage is 1 volt

Channel B: main voltage is 2 volts

To see the signal switching with a volt-meter you would put it on AC setting.


Wiring Diagram Exercise

I have located a computor data line wiring diagram for a 2001 Range Rover.

This is helpful for diagnosis because you can see how all the modules are connected and you can find pin-outs and pin-ins.

Locate a system that goes to "sleep" after a short time. what is it?

ABS control unit.

Awake voltage 0.29v   

Asleep voltage 0.12v

Wire we back probed Brown/yellow twisted pair.

Amp Drain.

Asleep : 0.92 amps

Awake : 2.35 amps

How long did it take to go to "sleep"?  5 min.

What made the system "wake up" Switch on the ignition.